Testosterone-Like Immunoreactivity in Hair Measured in Minute Sample Amounts: A Competitive Radioimmunoassay with an Adequate Limit of Detection

The study aimed to develop a radioimmunoassay capable of detecting testosterone-like immunoreactivity in small hair samples (5 mg), which is less than what was previously used. The assay, which utilized a polyclonal antiserum and a synthesized radioligand, achieved a limit of detection at 0.87 pg/mL, corresponding to 0.12 pg/mg of testosterone in hair. The average concentration of testosterone-like immunoreactivity found was 1.23 pg/mg in women and 2.67 pg/mg in men, with the use of pulverized hair samples resulting in significantly improved precision over non-pulverized samples. The study concluded that hair pulverization before hormone extraction is essential and that the detection limits are suitable for the intended purpose with 5 mg hair samples.